The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefor.
1. Field of the Invention
The invention relates to exploding foil initiator (EFI) systems for munitions and is directed more particularly to a low energy exploding foil initiator (LEEFI) system.
2. Description of the Prior Art
Exploding foil initiators (EFIs) are activated by a high current pulse exhibiting an extremely short rise time. The pulse is generated by discharging a high voltage capacitor through a spark gap switch. Spark gap switches have suffered from problems relative to manufacturing, reliability in operation, and high costs. A new LEEFI has been developed which operates at substantially lower energy levels than conventional EFIs. The new LEEFI has the potential to reduce size and cost of foil initiator systems by reducing the size of the high voltage capacitor and charging circuitry.
Spark gap switches are deemed to be less than optimal for LEEFI firesets. The reliability of the spark gap switches is reduced at voltages of less than 1500 V and therefore do not allow for full advantage of savings that could be derived from LEEFI operations which require 1000 V, or less. Further, spark gap switches are reliable only for a limited number of discharges. Accordingly, during and after manufacture, the number of tests performed on each switch must be tracked to ensure that overtest does not degrade performance in a weapon.
Accordingly, there is a need for a new switch, or fireset, for LEEFIs.
It is, therefore, an object of the invention to provide a fireset for use in conjunction with a LEEFI.
With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of a fireset for a LEEFI, the fireset comprising a first capacitor for storing a level of electrical energy sufficient to fire the LEEFI, the first capacitor being in electrical communication with the LEEFI, second, and third capacitors in electrical communication with the first capacitor for storing lesser levels of energy than is stored by the first capacitor, a diode in electrical communication with the capacitors for limiting charging of the second and third capacitors, and first and second resistors providing isolation among the capacitors. A trigger directs a pulse of electrical energy to a high speed switching transistor to dump the third capacitor. The third capacitor dumps through a silicon controlled rectifier (SCR) to short the second capacitor to ground, to decrease the level of energy stored by the second capacitor. The second capacitor discharges into a gate portion of a Metal Oxide Semi-conductor Field Effect Transistor MOSFET to turn on the second MOSFET and thereby dump the first capacitor to fire the LEEFI.